An anti-G suit typically is provided in a highly maneuverable aircraft, such as a fighter aircraft, in which aircrew are subjected to high G-forces during maneuvers, to prevent aircrew from suffering blackouts caused by retreating blood which empties from the head and upper body. The anti-G suit is connected to a G-force sensitive valve which operates to cause pressurization of the anti-G suit automatically when necessary to protect the aircrew. The valve includes a member which moves in response to the applied G-force. In use, the prior art G-force fluid control valve can be subject to substantial vibration. High vibrations can cause damage to the valve and/or cause turbulence in fluid flowing from a valve outlet. This can in turn degrade the performance of the valve.